1. Field of the Invention
The present invention relates to a recording and reproducing system, a recording apparatus, a reproducing apparatus, a recording medium, a recording and reproducing method, a recording method, a reproducing method, a program and a recording medium.
2. Related Art of the Invention
To begin with, a description will be given as to configuration and operation of a personal computer for reproducing data files such as an image file having image data and a voice file having voice data (refer to Patent Document 1, Japanese Patent Laid-Open No. 2000-235780 for instance).
The data files such as the image file and voice file are recorded on a recording medium such as a CD-ROM (Compact Disk-Read Only Memory) according to a predetermined file system.
The personal computer performs play list reproduction wherein it interprets a play list file in an HTML (Hypertext Markup Language) format describing reproduction order of the data files by using file names of the data files to consecutively reproduce a plurality of data files.
In the play list file in the HTML format, the data file to be reproduced is described by using the file name including a path name. And the data file is generally recorded on the recording medium via a file system by associating the file name with substantial data in the file. For instance, in the case of the CD-ROM, the file system in compliance with the ISO 9660 standard is used.
Therefore, to reproduce a reproduction file described in the play list file, a reproducing apparatus of reproducing the play list file requires the following procedure. That is, it first obtains a data file name described in the play list file, and then reads and analyzes information of the file system from the recording medium. And it identifies a record location of the data file to be reproduced, and then reads the data recorded at the record location so as to perform reproduction. To be more specific, in order to start the reproduction of the data file, it is necessary to search for and obtain the information on the record location based on the information of the file system.
Here, there is a problem that, if a large amount of data files are on the recording medium, it takes time to search for and obtain the information on the record location of the data file from the file system, causing a delay in a reproduction start time. Hereafter, this problem will be described in detail.
The information of the file system is generally managed in directories. For this reason, in the case where the data files are recorded in a hierarchy by using the directories, it is necessary, when obtaining the information on the record location of the data file, to trace the information of the file system for each directory downward from a root directory. Consequently, in a data structure in which the data file is located in a hierarchy deep from the root directory in particular, it is not possible to obtain the information on the actual record location of the data file without reading and analyzing the information of the file system for many directories.
The process of reading and analyzing the data of the file system has required certain processing time on a reproducing device, leading to the delay of the reproduction start time. And the data of the file system is not always consecutively recorded. Therefore, a head needs to seek in some cases in order to read the data of the file system from the recording medium when obtaining the information of the file system hierarchically for each directory. The time required for the seek is also a factor behind the delay of the reproduction start time.
Consequently, for a commercial-off-the-shelf device such as a DVD player, data readout speed from the recording medium is not high compared to the personal computer, and data processing speed of a built-in microcomputer is not high either. Therefore, in particular, the processing time in conjunction with the aforementioned data readout and analysis of the file system causes the delay of the reproduction time, and it is not possible to provide a play list reproduction function of good responsiveness.
It is generally thinkable, as regards such a problem, to speed it up by caching the data of the file system in an internal work memory. In the case where the data of the file system is cached in the internal memory by such a method, it is no longer necessary to read the data of the file system from the recording medium so that no delay arises in conjunction with data readout and the data of the file system can be analyzed at high speed by searching the data on the internal memory.
To cache and manage the data of the file system managed by the directory in the internal memory, however, it is necessary to cache it correspondingly to a directory name. And when searching for the data in the cache, it is necessary to search for the data of the file system corresponding to a desired directory by using the directory name as a key.
In this case, as the data of the file system is stored correspondingly to the directory name, there is a problem that a data capacity to be cached increases if the directory name is a long character string. When searching for the data in the cache, it is necessary to make a search by using the character string of the directory name as the key. Therefore, it requires a comparison process equivalent to the number of characters to ensure a match with the character string so that the search takes certain processing time. In the case where a directory tree is deep, it is necessary, as in the case of using no internal cache, to repeatedly search for the information of the file system for each directory in sequence from the root directory downward. This search process also takes certain processing time.
Consequently, for the commercial-off-the-shelf device such as the DVD player incapable of analyzing the data of the file system at high speed even when using the internal cache, there is a problem that it is not possible to provide the play list reproduction function of good responsiveness in the play list reproduction with the file name described.